Journal article

Ab initio many-body effects in TiSe₂: A possible excitonic insulator scenario from GW band-shape renormalization

  • Cazzaniga, M. Università degli Studi di Milano, Physics Department, Milano, Italy - European Theoretical Spectroscopy Facility (ETSF)
  • Cercellier, H. Institut Néel, CNRS and UJF, Grenoble, France
  • Holzmann, M. LPTMC, CNRS and UPMC, Paris and LPMMC, CNRS and UJF, Grenoble, France - European Theoretical Spectroscopy Facility (ETSF)
  • Monney, Claude Synchrotron Radiation and Nanotechnology Department, Paul Scherrer Institut, Villigen, Switzerland
  • Aebi, Philipp Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, Switzerland
  • Onida, Giovanni Università degli Studi di Milano, Physics Department, Milano, Italy - European Theoretical Spectroscopy Facility (ETSF)
  • Olevano, V. Institut Néel, CNRS and UJF, Grenoble, France - European Theoretical Spectroscopy Facility (ETSF)
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    08.05.2012
Published in:
  • Physical Review B - Condensed matter and materials physics. - 2012, vol. 85, no. 19, p. 195111
English We present both theoretical ab-initio results within the Hedin's GW approximation and experimental angle-resolved photoemission and scanning tunneling spectroscopy measurements on TiSe₂. With respect to the density-functional Kohn-Sham metallic picture, the many-body GW self-energy leads to a ≈0.2-eV band-gap insulator consistent with our STS spectra at 5 K. The highest valence and the lowest conduction bands are strongly renormalized, with a loss of k² parabolic dispersion toward a k⁴ shape. In particular, GW moves the top of valence moved toward a circle of points away from Γ, arising in a Mexican hat shape commonly associated with an excitonic insulator. Our calculations are in good agreement with experiment.
Faculty
Faculté des sciences et de médecine
Department
Département de Physique
Language
  • English
Classification
Physics
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/302507
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